Anodic pulse enhanced electrocrystallization (APEX) of tin

Addition agents are essential for deposition of quality tin films from acidic sulfate baths. Plating studies indicated that the initial substrate condition and tin nucleation were the most important factors in the growth morphology and ultimate smoothness of the electroplated tin. Addition agents were very effective and necessary for proper initial growth of tin on copper. The data showed, however, that once a satisfactory tin layer was initiated, the role of additives was less important to continued level growth. Based on these findings, an experimental program was developed to investigate ways to modify the nucleation, using electrochemical techniques in place of organics